I have a Intel S5520HCT motherboard with duel Xeon L5630 running Windows 2008 R2. I am using Kingston DDR3 1066 Parity Registered ECC memory (KVR1066D3D8R7S/4G). On the Kingston website it says this RAM is certified for my motherboard and CPUs.
However, when I install 48GB of RAM (all channels filled) the performance is so poor the system is almost unusable and the CPU utilization is near 100% when I run even the most simple program. When I remove 2 RAM modules from a channel on each CPU/memory-controller (now 32GB total) the performance vastly improves to an acceptable level.
I thought this may be a problem with the Registered memory, so I took non-registered ECC 4GB RAM (KVR1333D3E9SK2/8G) from two other machines and installed them. But shockingly I saw the same behavior. So it is obviously something with the motherboard.
Has anyone experienced this behavior before, and if so how did you solve it?
Thanks Edward. This worked!